Bastion is a demi-plane controlled by the Empire of Thyatis. In an OD&D campaign, it has 5 dimensions. Magic works normally on Bastion, identical to that of the Prime Materiel Plane, and there are no Planar biases. The Plane itself is roughly 10 miles in diameter, not large as Planes go; it is easily large enough for the purposes to which Thyatis needs it for. The Planar boundaries glow half the “day” and grow dark the other half, creating a “day” and “night”. The entire Plane is filled with air. Several solid masses float within the Plane, with the largest at the center. There is no gravity as such in the Plane, except within 500’ of one of the floating earth masses. If you are within 500’, “down” is towards the surface of an earth mass. Beyond that, “down” is whatever direction a creature chooses, but one does not fall. The Planar boundaries are unusual in that if one tries to push them, whatever they use will leave a slight indentation, then “pop” back into place when the pressure is released. However, if one pushes hard enough, they will pass through – to emerge within the demi-Plane directly opposite their starting position. The “pucker” left by their passing will seal behind them. One has to make a determined push to do that, however. It is possible to walk along the demi-Planar boundary without passing through – the surface feels somewhat spongy. This boundary cannot be damaged, cut, dug, or marred or marked in any way (any marking or writing will fade within one round).
Most of the earth masses that float within the boundaries of Bastion are little more than 100’ in circumference, and generally only half that deep. They are all fixed in place – they do not move within the demi-plane, and indeed cannot be moved. Each has at least one spring from which fresh water bubbles, never seeming to be exhausted but also never seeming to flood the demi-plane. The largest landmass, fixed in place at the center of the demi-plane, is 1.2 - 1.25 miles in diameter and 1,200’ or so deep at the rim, forming a rough disk, and it has several such springs. It is 1,500’ thick at its center, with a mound rising on both “faces” of the disk towards the middle. This is Bastion itself. It is honeycombed with caverns and chambers, and its surface similar to that of a warm, temperate Prime Materiel planet in vegetation (indeed, not dissimilar to the climate near Thyatis City). There is one addition, though, unique to the demi-plane: a large bush that flowers every morning, the flowers ripening into fruit by nightfall, which can then be harvested and eaten to provide nourishment every day.
Bastion is used by the Empire as a redoubt and arsenal. There are permanent, keyed Gates within Bastion, leading to Retebius City and the Zendrolion in Thyatis City. These Gates are magic items, and fully intelligent, with an intelligence of 18 (Genius), telepathy and ESP, (and high Sense Motive skills in 3E), and True Seeing ability. They function as the first line of defense and as guards: The Gates function only for authorized personnel, and are non-functional for others who simply pass through an area on the Prime Materiel Plane into a room, rather than being transported to Bastion, and thus may not even notice there is a Gate present. Enchantments are in place to make the Gates undetectable to detect magic spells, and the Gates are always protected as if by Mind Blank. This allows the Thyatian government to move forces to and from Bastion, but limits access to others.
Bastion is laid out as a “park”, with paths and roadways interconnecting buildings and cavern entrances, all of which are of human, dwarven, and elven engineering: Thyatians of all races contributed to the architecture of this plane, blending their various styles into a uniquely Thyatian atmosphere. There are scores of dragon-caverns (especially hatcheries), sphinx & griffon lairs, roc nests, and pegasus & griffon aeries, as well as havens for even stranger creatures. This is where RAF mounts are bred. Many of the floating landmasses are used as lairs by Thyatian dragons and sphinxes. It serves as the trans-planar base and mustering point for the RAF & KoA. There is also a bath & spa, and other amenities for those stationed here. A Cohort of the Tagmata is usually on duty here, as are members of the Thyatian special services (members of their covert operations agencies, such as the Magistranoi) and elite treasury guards. One of Thyatis’ Imperial Treasuries is located in a highly protected vault within Bastion, which serves as the Empire’s emergency reserve. There is also an arsenal within Bastion, stocked with weapons, including magical items, and there are smithies and forges for the manufacture of more. Another vault contains preserved tissue samples of every flying mount & RAF or KoA member in Thyatian service, and of virtually all prominent Thyatians in government service. These tissue samples are kept preserved so that they can be Cloned in the event of their demise. Additional areas of Bastion serve as research labs, both mundane and magical, conducted by the Imperial Armed Forces, and there is a large research library and a “Library of Thyatian Knowledge” on Bastion. Other portions are set aside for religious use, the Clerical branch being important to the welfare of the Imperium. The Foresters have an “office” on Bastion, in a wooded grove, as do a few other select Thyatian Fighting Orders. Special training is conducted here, and secret missions launched from here. Since the war with Thothia, new laboratories and enchanting areas have been carved out – to create Constructs and undead. The Thyatian Empire may not have originated such units, but the Emperor has vowed to never be caught short again. Thyatis, being much larger and several orders of magnitude more populous and wealthy than Thothia, it quickly rectified this difficiency once they poured resources into it. A diverse variety of constructs (though no Drolems) are created on and stored within Bastion, and experiments are being conducted for incorporating undead into regular units (mainly to absorb casualties), though most of the Thyatian military is opposed to using undead on any significant scale and since the end of the Thyatian Civil War, it is even less likely that undead will be used by Thyatis as military units. But most see constructs as a useful tool, "heavy artillery" and as a fine example of Thyatian military engineering.
Most of the smaller floating earth masses in Bastion are used by dragons, sphinxes, and other intelligent creatures loyal to Thyatis as lairs, and a number of Master-level (or Epic, in 3E) Adventurers who serve Thyatis are permitted to be based from here. The Emperor also has a “get away” villa located on Bastion itself, with a Gate connected to the Imperial Palace. Note that in extremis, all the Gates can be shut down, to prevent (or at least limit) invasion by enemies. One of the purposes of Bastion is to serve as the headquarters for a resistance and launching-point for counter-attacks should the rest of the Empire be occupied, so it is well stocked to provide everything an independent, self-contained and self-sufficient base needs. It is also used by the Empire for strategic mobility: units can move from Thyatis City or Retebius to Bastion using the Gates here, then be Gated from Bastion to elsewhere using normal spells.
Background
After the Spike Assault, Thincol devoted his efforts as Emperor to rebuilding the Empire and insuring that it would never be in danger of falling again. To that end, he attempted to come up with a means of insuring its survival, even a plan for reproducing his own efforts during that dark time. Institutionalizing a practice and making advanced preparations is a very Thyatian thing to do, but more to the point Thincol realized that there was a certain amount of fortune or providence involved in his victory over the Alphatians in the Spike Assault War. Thyatis may not be so fortunate as to have a Thincol the Brave on hand to organize an ad-hoc counter-offensive against its enemy in the future, but it will remember the Emperor who not only led that counter-attack but made preparations to insure its security for all time.
The Empire also needed a secret base, protected from normal magical and non-magical espionage, from which to launch covert missions and military strikes. Almost all of the bases it had at the time had long since been discovered by its enemies. Emperor Thincol had a vision of what Thyatis needed, but discarded as insufficient every option his advisors presented him with. None seemed like they would provide enough security or would be preserved in extremis. Finally, Tiella Tien-Tang reminded him of a small demi-plane they had visited back in their adventuring days. At the time, it had been inhabited by a multi-planar faction, which Thincol’s adventuring friends had decimated and looted. But it was still dangerous, uncleared, and not entirely mapped out. For several years, the Emperor had his hands full in his efforts to rebuild the Empire and turn its fortunes around. But in 967 he started sending teams of Thyatians who had proven themselves to him during his counter-attack against the Alphatians and in his recovery efforts after that to finish clearing out and mapping the demi-plane, which the Thyatians now named Bastion. By 972, this was done, and the Thyatians began to construct their base here. The base was completed by the time of the “Buildup” (AC 1004) that led into the Final War with Alphatia (aka “Wrath War”, AC 1005-1009).
However, Bastion’s forces suffered as much as the rest of the Empire from the enervating efforts of Valerias: troops were indolent and self-indulged with debaucheries, standards lax, and everything suffered as a result. The armories were not stocked and sufficient supplies not laied away. Deficiencies went unreported – instead, false reports were sent to the Imperial General Staff detailing missions that never occurred and lauding efforts that were never made. Thus the Emperor thought he had a base providing a significant contribution to the war effort, but he was being misinformed. These subterfuges were uncovered late in 1006, and those responsible relieved, charged with crimes, and imprisoned. Since then, independent “Inspector Generals” check out the status of Bastion every few months and report any deficiencies. A new commandant was appointed, who brought in his own staff and began whipping things into shape. This took several months, and Bastion wasn’t able to make a significant contribution to the Thyatian war effort until well into AC 1007. The one positive benefit from all this, however, was that Thyatis’ enemies did not even suspect the existence of such a base.
By this point Bastion’s focus was dedicated to hosting reserve forces for the defense of mainland Thyatis, reaction forces to counter potential direct Alphatian attacks into Glantri, and strike teams that were inserted into Alphatian-held territory, even into Alphatia itself, to perform covert missions and sabotage. But it came to its own during the great naval clash of AC 1008. Members of the RAF and KoA sortied from Bastion via multiple Gates to strike Alphatian sky and sea ships by surprise, helping the Thyatians turn back the attempt to invade Thyatis. During this battle they decimated a regiment of Alphatia’s Imperial Guard, one that had been created during the buildup to the war using aerial mounts in emulation of the RAF, which the Alphatians hoped would be the key to defeating Thyatis once and for all.
From that point to the end of the war, Bastion served as a rallying point for Thyatian reserves, and Thincol continued to see it as his “ace in the hole” even during the Alphatian march across Thyatis later in the war, he believed it would be a key to turning the tide towards an eventual Thyatian victory, as he did in the Spike Assault War. Bastion was to be the cornerstone in the defense of Thyatis City, but ultimately Thincol decuded to quit the field, seeing that the war to defend Glantri was undoing his life’s work, with Thyatis having little to show for its efforts and much to lose, doing the bulk of the fighting while its allies were shielded from the brunt of the war. By this point, however, Eriadna suspected that Thyatis had a hidden reserve of strength, and for this reason she was willing to come to peace terms with Thyatis rather than attempting to finish if off – indeed, generous peace terms that treated Thyatis as a nation needing respect, requiring the Alphatians to withdraw from all the Thyatian territory they had conquered.
Since the end of the war, Bastion has been a behind-the-scenes engine of Thyatis’ revival. Within this base, Thyatian aerial forces have been regrown – often literally, through the use of Clone spells reviving Thyatian heroes and slain mounts, all in a way that was out of sight of most observers. Indeed, oen of the main reasons why Thincol chose to place a base on another Plane is that it rendered it secure from most forms of espionage and magical divination & scrying, preferred tools of the Alphatians and many other magically-inclined foes.
Bastion now serves as one of the hubs of the Thyatian Empire’s strength, a primary means of both defense and power projection. The Emperor allows select high-level Thyatians to base themselves here, which is not entirely – or even mainly – an act of generosity on his part. Giving them this priviledge means that they are at hand to defend Bastion should it ever be attacked.
As with most secrets, many nations and powerful individuals would richly reward anyone who could give them information about this base, and the Empire would do much to keep it secret – and be unrelenting in retribution against any who disclose its existence.
I especially like the idea of cloning centers for elite forces. That's something I hadn't thought about before, but it raises some interesting possibilities. Such facilities could be used as intended, but just think what would happen if someone (an enemy agent, a wizard with a grudge, etc..) were to clone these individuals prematurely. Nice adventure potential.
I do have a few questions for you. Who (or what) were Bastion's original inhabitants? Are there any traces of them left... perhaps even traces that the Thyatians wouldn't know about? Were the former inhabitants decimated, or just driven away? Do they still lurk in the shadows plotting their revenge?
Are there any other planar bridgeheads that the Thyatians have. One problem with establishing such bases is the potential for extra planar warfare. What effects would this have on the Empire?
This is a dangerous door to open though. In most fantasy campaigns, people do never take full advantage of what it is possible to do with magic does one have the imagination. In most campaigns, there seems to be a gentleman's agreement that certain methods of warfare for instance are not used.
If they are to be used, however, this is surely the way to do it. Ofcourse, for Thyatis, the problem is that if their enemy is one who uses magic, like say Alphatia, this weapon could easily be used against them. The Alphatians might just disable the gates while the Thyatian forces are inside the plane, trapping them, unable to participate in the conflict at all.
The other consequence of using such ideas, is that all countries would be using these methods to some level or other. Granted, not all countries have the same potential for magic, but countries like Alphatia and Glantri will certainly have alot of tricks up their sleeves. So, what kind of ideas might other countries use to defend themselves against magical warfare?
Havard
Anyway, back to the topic at hand. I wrote some musings along these lines a while ago that can be found in the vaults:
http://dnd.starflung.com/planrwar.html
What other high level spells might be used in Mystaran warfare?
Summon monster spells (of all levels) are a no brainer. Their only limitations are the duration and range of the spell which are rather short.
Soul Bind might be used to prevent the resurection of powerful foes. But where would these souls be stored? Perhaps in some military instalation deep in the heart of a country's territory (or on a planar outpost). This is one spell that would counteract James' proposed cloning facility, although it is quite a high level to be used all the time. Think of the adventures associated with this possibility, as the PCs struggle to free bound souls of heroes throughout time.
Trap the Soul might work in a similar manner, and since it is an 8th level spell instead of 9th, it might find (slightly) more use.
Any other ideas?